The present invention relates to novel nitrogenized electronic conductive polymers and to their preparation processes. These polymers are suitable for forming the electrochromic layer of an electrochromic display cell, as well as for forming the active electrode material of an electrochemical generator.
Apart from these specific applications, the conductive polymers according to the invention can be used as components for elements of passive or active electronic circuits, such as electromagnetic shields, as a material for eliminating electrostatic charges, as a matrix or binder used in the composition of composite materials, as a voltaic converter and as an electrode material with specific properties.
As an electrode material, the polymers according to the invention can be used in fuel cells, in analytical chemistry, in chemical and electrochemical catalysis for determining the potential or pH of a solution for protecting against corrosion.
The polymers according to the invention can also be used as gas, water, radiation and similar detectors, as an antiradar shield, or as an ionic gate.
In summarizing, the electronic conductive polymers according to the invention can be used in all fields normally employing conductive materials.
Among the known electronic conductive polymers, two types of materials deserve particular note. The first type relates to polyacetylene and its derivatives and the second type to polyaniline and its derivatives.
Polyacetylene of general formula (CH).sub.x exists in three forms, namely an undoped, neutral form (I), a p-doped, oxidized form (II) and a n-doped, reduced form (III). These forms can be symbolized by the following chains: EQU (I) --CH.dbd.CH--CH.dbd.CH--CH.dbd.CH--CH.dbd.CH-- EQU (II) .dbd.CH--CH.dbd.CH--CH--CH.dbd.CH--CH.dbd.CH-- +X.sup.- EQU (III) .dbd.CH--CH.dbd.CH--CH--CH.dbd.CH--CH.dbd.CH-- +Y.sup.+
in which X.sup.- and Y.sup.+ respectively represent an anion and a simple or complex cation. As the anion, reference can be made to C10.sub.4.sup.-, C1.sup.-, Br.sup.-, I.sub.3.sup.-, FSO.sub.3.sup.-, SO.sub.4.sup.2-, BF.sub.4.sup.-, PF.sub.6.sup.-, etc. and as the cation to Li.sup.+, Na.sup.+, K.sup.+, etc.
Polyacetylene is distinguished by the fact that its structure is constituted by a succesion of single and double carbon -carbon bonds. Due to its relatively simple and in part crystalline structure and its electroactive properties (electrical conductivity of 1000 ohms.sup.-1 cm.sup.-1) giving rise to numerous applications, considerable significance has been attached to polyacetylene. Unfortunately this material is much too unstable and reactive to give any hope of obtaining time-stable application forms.
Due to its stability, considerable interest has also been attached to polyaniline, which is distinguished by the fact that it can undergo two charge transfer types. It exists in a large number of forms and particularly in an insulating reduced form (1), a first insulating oxidized form (2), which is conductive when protonated, and a second, also conductive, oxidized form (3). These three forms exist in a neutral or basic medium. In the acid medium, other protonated forms exist, but no reference will be made thereto here.
The three forms (1), (2) and (3) are respectively symbolized by the chains: ##STR1## in which X.sup.- represents a single or complex anion. The anion can be C10.sub.4.sup.-, SO.sub.4.sup.2-, C1.sup.-, F.sup.-, Br.sup.-, I.sup.-, I.sub.3.sup.-, BF.sub.4.sup.-, PF.sub.6.sup.-, FSO.sub.3.sup.- etc.
Form (2) is obtained by oxidizing form (1) leading to the removal of an electron and a H.sup.+ by a nitrogen atom. In the same way, form (3) is obtained by oxidation of form (1) leading to the removal of an electron by a nitrogen atom. Form (3) should be called phenylene polynitrenium.
Polyanaline is a conductive polymer with a very high mass capacity. Experimentally the measured mass capacity is close to 150 Ah/kg. Unfortunately, its electrical conductivity of 1 to 10 ohms.sup.-1 cm.sup.-1 is relatively low, which limits its applications.